Electronic Communication Systems 2nd Edition by Roy Blake

Exercise 12

A transmitter power amplifier has a gain of 30 dB and an efficiency of 75%. Its output power is 100 watts.
(a) What signal power must be provided at the input
(b) How much current does the amplifier draw from a 100 volt power supply
(c) Suppose this amplifier is to be amplitude modulated using high level modulation. How much power must be supplied by the audio amplifier, for 100% modulation
(d) What will be the output power with 100% modulation, assuming the efficiency is the same with and without modulation